Attorneys for Google, Apple, Adobe Systems and Intel have appealed a judge's decision to throw out a proposed settlement in Silicon Valley's employee hiring case.

Attorneys for Google, Apple, Adobe Systems and Intel have appealed a judge's decision to throw out a proposed settlement in Silicon Valley's employee hiring case.

Attorneys for the companies filed a petition Thursday evening with the U.S. Court of Appeals for the 9th Circuit, appealing Judge Lucy Koh's recent decision to throw out a proposed US$324.5 million settlement. Plaintiffs in the class-action case, Silicon Valley technology workers, accuse executives at the companies of conspiring not to hire each other's workers between 2005 and 2009, which they say suppressed their wages and restricted their mobility.

Federal district court Judge Koh rejected the settlement in early August, on the grounds that it was too low given the strength of the evidence -- specifically emails between executives -- that would support a trial. That decision was a "clear error as a matter of law," attorneys wrote in the Thursday filing.

"The district court applied a mechanical formula that overrode sensitive judgements of the class's own counsel based on confidential information regarding the serious risks posed by their claims and their chances of success at trial," it said.

"The ruling will inflict significant harm on all parties and the class action procedure," it said.

A proposed start date for a trial has already been set for Jan. 12. Attorneys for both the defendants and plaintiffs have until Monday to file a joint statement regarding the proposed pretrial and trial dates.

If there is a trial, the reputations of several major technology companies could be re=evaluated, particularly if executives like Google executives Larry Page or Eric Schmidt take the witness stand.

Google and Intel declined to comment beyond the filing. Apple and Adobe did not immediately respond for comment.